[C++] Implement IO interface that can read and write to a fixed-size mutable buffer

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Here is an example implementation in a thirdparty user of Arrow: https://github.com/ray-project/ray/blob/master/src/numbuf/python/src/pynumbuf/memory.h

cc @pcmoritz @robertnishihara

Reporter: Wes McKinney / @wesm
Assignee: Wes McKinney / @wesm

Related issues:

• Arrow 0.3 release (blocks)

_{Note: This issue was originally created as ARROW-656. Please see the migration documentation for further details.}

[asfimport]

Wes McKinney / @wesm:
PR: #486

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Uwe Korn / @xhochy:
Issue resolved by pull request 486
#486